I was visiting someone in NorCal. There was an 84 XJ6 for sale. Had a slight miss. What should I look for. I let it run for about 30 minutes(didn't drive it) the oil pressure was normal and the temp gauge was in the normal range. The miss didn't get any worse or any better. No leaks that I saw. Any help would be greatly appreciated. As I'm headed back up in the morning.
Larney

 

Like any other car it could be as simple as an old fashioned ignition misfire: old spark plugs, faulty distributor cap or plug wires, etc.

Or it could be an injector acting up.

Or it could be one cylinder with low compression---possibly from a blown head gasket.

Cheers
DD

 

If you had the compression tester you could do the compression test in all of about 15 minutes before you commited to it. If it had bad compression, in my opinion "NO WAY". unless it was cheap enough.

 

Hi,
do not expect the engine to run perfectly smooth, they always miss a little especially if they have sat for a while, it takes these engines a while to go through its warm-up cycles, and after all, it is an old engine, old gasoline, old old.

if the temperature seems fine, and no white smoke comes out the exhaust when engine is cold or warm, and the coolant does not look like it is mixed with oil, it's not a cylinder head gasket.

if the missing is only during idling, take the car for a 1-hour drive, 30 minutes each way, take it to 80 mph and see how it feels, it should tell you exactly how it is doing. Watch the temperature, it should go down, not up, during fast highway driving. It will get hotter in stop and go traffic, and then the auxiliary cooling fan should come on.

Could be something as simple as an expired Oxygen Sensor or the sensor needing a better ground, I added a separate ground to my O2 sensor and it started to run a lot smoother.

Good luck !

 

Interior in good shape 7 or 8/10. One slight crack on the wood grain by heater controls. Needs a good cleaning. Body and exterior paint looks like an 8/10. So what should the compression be around 120? I'm hoping for the best. If compression checks out then I might go ahead and take the chance. Asking 3000. She's putting it on the market this weekend. I'm trying to get there first... Wish me luck.
Larney

 

all the wood grain dash panels in Jaguars start to show cracks after 20 years, use Pledge furniture polish to clean and shine it. The more cracks, the more character and patina.

look for rust bubbling at the bottom of the front and rear windshields. Typical place for rust, they all do it.

check that the Headliner is not collapsed, Check the electric windows and sunroof operation.

check the a/c and the heater: (warm up the car first).
1) place the Mode Switch in AUTO,
2) control the temperature by turning the TEMP control to 65 and then to 85 a number of times. min. to max. and viceversa.
(takes about 10 to 20 seconds for the system to change from COOL to HEAT in the 1984 model).

check the wipers:
move the switch down for intermittent mode, ( 1 wipe every half hour , ha ha)
move the switch up two steps for "normal" slow speed,
move the switch up another step for a faster slow speed.
(NOTE: there is no "FAST" speed, the wipers in these cars are very lazy).
(to operate the WASHER, press the button on the end of the switch).

Luck has been wished onto you.

 

More like 140-ish, but you might see 120 if the engine has lots of miles. Of course, for misfire detection you're looking for a cylinder that is way below the others


Cheers
DD

 

Elaborating a bit on Jose's remarks.....

It is typical or common for these engines to have a slightly rough * idle *. Not an outright misfire like a dead cylinder or disconnected spark plug wire.... but a slight tremble or roughness. It goes away entirely above idle. You should not feel a misfire while driving along, for example.

If this ^^ is what's happening I wouldn't be very concerned.


Cheers
DD

 

Thanks for all the comments. I'll keep you all updated on my journey.
If bought I'm sure I'll have more questions and need more help...
Larney

 

my punto exactamente Doug, many variables affecting idle in an old 4.2 liter engine, but once the engine is under load, all that coughing and flem usually disappear, assuming the engine is good overall.

The 3.8 liter carbed engine is even rougher at idling, but once it takes off, it starts to sing the Macarena.

larney, just listen to the engine, it talks clearly.